Preheat the oven to 375 degrees F. Place the water and spinach in a saucepan . Wilt the spinach, pressing down the spinach with the back of a spoon, about 45 seconds. Drain the spinach, squeezing out the spinach tightly and reserve the liquid. Pour the liquid into a mixing bowl with 4 tablespoons of the butter. The butter will melt and cool the liquid to 110 degrees F. Stir in the yeast and dissolve the yeast. Add the beaten egg, sugar, salt , and black pepper. Finely chop the spinach and add to the yeast mixture. Add the flour and mix well with a wooden spoon until the dough comes away from the sides of the bowl. Using your hands, form the dough into a ball. Lightly oil a bowl. Place the dough in the bowl and turn the dough once. Cover the dough with plastic wrap and place in a warm, draft-free place until the dough doubles in size, about 1 hour. Butter 6 over-sized muffin tins . Invert the dough onto a floured surface and punch it down with your fist. Fold each side in and tuck the ends into the center. Repeat. Put the dough , seam side down and divide the dough into 6 six equal portions. Using your hand, gently roll the dough into a ball. Place the rolls in the prepared pan. Sprinkle the rolls with kosher salt and cheese. Cover and let rise in a warm, draft-free place until in doubles in size, about 1 hour. Bake the rolls for about 30 minutes, or until golden brown. Remove from the oven and place on a wire rack to cool before removing from the pan.